Well Kill Simulation of Gas Drilling When Drilling into Gas Reservoir

Abstract Aiming at the situation of encountering high-pressure gas reservoir in gas drilling, a well-kill mathematical model is established using multi-flow theory. Then the simulation of bottom hole pressure and casing pressure during well kill is demonstrated under different good kick parameters. The results show that the successful well kill only depends on a reasonable combination of initial casing pressure, kill rate and kill mud density. As the maximum initial casing pressure can be determined, the other two well-kill parameters can be changed. A combination of low kill rate and low kill mud density may lead to a failure in well kill due to the impossibility of forming an annular mud column. A reasonable combination of kill rate and kill mud density can guarantee the success of well kill, which contains two cases. One is that the formation pressure is balanced with no casing pressure after a period of well kill, and the other is the formation pressure can only be balanced with a certain casing pressure. Over-weight kill mud may fracture the formation, which can cause complicated well control risk. This simulation is instructive for the design of well kill in gas drilling.